Cleveland Potash says its performance has improved since last year &#160;

IAN FORSYTH/GETTY IMAGES

Marcus Leroux

Friday August 07 2015, 1.01am, The Times

Miners at Britain’s biggest and deepest mine have been warned by management not to jeopardise their future by going on strike.

The Israeli-owned Cleveland Potash mine, near Boulby in Redcar and Cleveland, lost money last year and in the second half of 2013, according to a letter sent to the 1,000 staff last month. Union members voted last month to ballot for strike action but later reached an agreement with management.

In the letter, the mine’s managing director warned of the repercussions of a strike for the loss-making mine.

David Zvida, who was appointed by Israeli Chemicals last year to turn around the plant, wrote to staff: “Should you choose to take any form of industrial action, then this will surely prevent us from achieving